The police killing of unarmed African-American George Floyd shows the "true face" of the United States and its oppression of the peoples of the world, including its own, Iran's supreme leader said Wednesday.

"The fact that a policeman has cold-bloodedly pressed his knee on the throat of a black man until he died and that other policemen watched on without doing anything is nothing knew," Ayatollah Ali Khamenei said in a televised speech.

"It is the truce face of America, it's what it has always done all over the world -- in Afghanistan, Iraq, Syria and other countries, and before that in Vietnam.

"It is the normal course of action of the United States, it's the truce face of their regime," Khamenei said.

"These are realities that have always been camouflaged or hidden, but they are not new," he said in a speech on the 31st anniversary of the death of his predecessor, Ayatollah Ruhollah Khomeini.

Protests sparked by Floyd's killing by a white police officer in Minneapolis, Minnesota, have raged across the United States for a week and President Donald Trump has ordered the military to intervene.

Iran's supreme leader Ayatollah Ali Khamenei hits out at the United States in his first public comments since deadly weekend US air strikes on pro-Iran fighters in western Iraq
Iran's supreme leader Ayatollah Ali Khamenei hits out at the United States in his first public comments since deadly weekend US air strikes on pro-Iran fighters in western Iraq KHAMENEI.IR / -

The once-in-a-generation unrest has coincided with the world's deadliest coronavirus outbreak in the United States.

Epidemiologists have voiced concern that the thousands of people protesting at close quarters, coughing violently when hit by police tear gas, will lead to a new upsurge in infections.

"Thank God, (US leaders) have already been discredited by their actions -- their handling of the coronavirus has discredited and shamed them around the world," Khamenei said of the 106,000 deaths from COVID-19 already registered in the United States.

Iran had itself faced strong criticism from its arch-foe the United States when it was reeling from one of the world's highest COVID-19 death tolls earlier this year.

As of Wednesday, Iran's health ministry declared a total of 8,012 deaths, although that figure has been dismissed by some as underreported, including by Washington.

Tensions between Tehran and Washington escalated sharply in 2018, after Trump unilaterally withdrew the US from a landmark nuclear agreement and reimposed crippling sanctions.

Coronavirus Afghanistan Iraq Trump